Cyanidation is the go to hydrometallurgical method for the recovery of gold from ores on a commercial scale. The only other commercial process used to recover gold into solution from whole ore is thiosulphate leaching which is commercially practiced at Barrick’s Goldstrike mine in Nevada, USA, which has operated in this way since late 2014.
The commercial application of gold leaching using cyanide has existed since the 1890’s and its implementation allowed the processing of gold ores that were previously unfeasible using pre-existing gravitational recovery / amalgamation methods and the chlorination method.
The chemistry of gold extraction by cyanide is explained chemically through the Elsner equation;
4Au + 8 NaCN + O2 + 2H2O à 4 Na[Au(CN)2] + 4 NaOH
It is clear that the process requires both cyanide and oxygen for the dissolution of gold to proceed and so both need to be maintained at sufficient levels to provide efficient gold leaching.
Many minerals that may also be present in your ore can impact the levels of cyanide and oxygen available for the cyanidation process so the optimisation of the leaching stage is an ore specific task that GSL have the expertise and experience to provide.
The below links detail the testing that GSL offers to its clients in this area, however if you feel your requirements are not covered in the below topics do please contact GSL and enquire: